From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3F24DC4320A for ; Sun, 1 Aug 2021 07:36:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 18A2B61042 for ; Sun, 1 Aug 2021 07:36:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231142AbhHAHZ4 (ORCPT ); Sun, 1 Aug 2021 03:25:56 -0400 Received: from mga02.intel.com ([134.134.136.20]:28526 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230519AbhHAHZy (ORCPT ); Sun, 1 Aug 2021 03:25:54 -0400 X-IronPort-AV: E=McAfee;i="6200,9189,10062"; a="200472323" X-IronPort-AV: E=Sophos;i="5.84,286,1620716400"; d="scan'208";a="200472323" Received: from fmsmga002.fm.intel.com ([10.253.24.26]) by orsmga101.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 01 Aug 2021 00:25:45 -0700 X-IronPort-AV: E=Sophos;i="5.84,286,1620716400"; d="scan'208";a="519772111" Received: from twinkler-lnx.jer.intel.com ([10.12.91.138]) by fmsmga002-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 01 Aug 2021 00:25:42 -0700 From: Tomas Winkler To: Greg Kroah-Hartman Cc: Alexander Usyskin , linux-kernel@vger.kernel.org, Tomas Winkler Subject: [char-misc-next] samples: mei: don't wait on read completion upon write. Date: Sun, 1 Aug 2021 10:25:32 +0300 Message-Id: <20210801072532.8668-1-tomas.winkler@intel.com> X-Mailer: git-send-email 2.31.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Alexander Usyskin The original mei driver communication was strictly write command and receive response flow, the completion of write was determined when response was ready using select(). This paradigm is a long time not true. There can be write without a response and an unsolicited read. The driver is capable of handling those. Adjust also the sample code and remove select() on read() from the write flow. Add select to the read flow to showcase how to do the read with a timeout. Signed-off-by: Alexander Usyskin Signed-off-by: Tomas Winkler --- samples/mei/mei-amt-version.c | 51 ++++++++++++++++++++--------------- 1 file changed, 30 insertions(+), 21 deletions(-) diff --git a/samples/mei/mei-amt-version.c b/samples/mei/mei-amt-version.c index ad3e56042f96..867debd3b912 100644 --- a/samples/mei/mei-amt-version.c +++ b/samples/mei/mei-amt-version.c @@ -154,31 +154,52 @@ static bool mei_init(struct mei *me, const uuid_le *guid, static ssize_t mei_recv_msg(struct mei *me, unsigned char *buffer, ssize_t len, unsigned long timeout) { + struct timeval tv; + fd_set set; ssize_t rc; + tv.tv_sec = timeout / 1000; + tv.tv_usec = (timeout % 1000) * 1000000; + mei_msg(me, "call read length = %zd\n", len); + FD_ZERO(&set); + FD_SET(me->fd, &set); + rc = select(me->fd + 1, &set, NULL, NULL, &tv); + if (rc > 0 && FD_ISSET(me->fd, &set)) { + mei_msg(me, "have reply\n"); + } else if (rc == 0) { + rc = -1; + mei_err(me, "read failed on timeout\n"); + goto out; + } else { /* rc < 0 */ + rc = errno; + mei_err(me, "read failed on select with status %zd %s\n", + rc, strerror(errno)); + goto out; + } + rc = read(me->fd, buffer, len); if (rc < 0) { mei_err(me, "read failed with status %zd %s\n", rc, strerror(errno)); - mei_deinit(me); - } else { - mei_msg(me, "read succeeded with result %zd\n", rc); + goto out; } + + mei_msg(me, "read succeeded with result %zd\n", rc); + +out: + if (rc < 0) + mei_deinit(me); + return rc; } static ssize_t mei_send_msg(struct mei *me, const unsigned char *buffer, ssize_t len, unsigned long timeout) { - struct timeval tv; ssize_t written; ssize_t rc; - fd_set set; - - tv.tv_sec = timeout / 1000; - tv.tv_usec = (timeout % 1000) * 1000000; mei_msg(me, "call write length = %zd\n", len); @@ -189,19 +210,7 @@ static ssize_t mei_send_msg(struct mei *me, const unsigned char *buffer, written, strerror(errno)); goto out; } - - FD_ZERO(&set); - FD_SET(me->fd, &set); - rc = select(me->fd + 1 , &set, NULL, NULL, &tv); - if (rc > 0 && FD_ISSET(me->fd, &set)) { - mei_msg(me, "write success\n"); - } else if (rc == 0) { - mei_err(me, "write failed on timeout with status\n"); - goto out; - } else { /* rc < 0 */ - mei_err(me, "write failed on select with status %zd\n", rc); - goto out; - } + mei_msg(me, "write success\n"); rc = written; out: -- 2.31.1